…richton

Add unaligned volatile intrinsics

Surprisingly enough, it turns out that unaligned volatile loads are actually useful for certain (very niche) types of lock-free code. I included unaligned volatile stores for completeness, but I currently do not know of any use cases for them.

These are only exposed as intrinsics for now. If they turn out to be useful in practice, we can work towards stabilizing them.

r? @alexcrichton

impl PartialEq+Eq for BuildHasherDefault

`BuildHasherDefault`is only one way of implementing `BuildHasher`. Clearly, every `BuildHasherDefault` for the same type `H` is identical, since it just uses `Default<H>` to construct `H`. In general, this is not true for every `BuildHasher`, so I think it is helpful to implement `PartialEq` and `Eq`.

…tolnay

Allow declaring existential types inside blocks

fixes rust-lang#52631

r? @dtolnay

Stablize Redox Unix Sockets

I don't know if I did this correctly, but I basically spammed the `#[stable]` attribute everywhere :^)

…s, r=cramertj

Prefer `Option::map`/etc over `match` wherever it improves clarity

This isn't intended to change behavior anywhere. A lot of times statements like `match x { None => None, Some(y) => [...] }` can be rewritten using `Option::map` or `Option::and_then` in a way that preserves or improves clarity, so that's what I've done here.

I think it's particularly valuable to keep things in `libcore` and `libstd` pretty/idiomatic since it's not uncommon to follow the `[src]` links when browsing the rust-lang.org docs for std/core. If there's any concern about pushing style-based changes though, I'll happily back out the non-std/core commits here.

clarify pointer offset function safety concerns

Release notes: add some missing 1.28 libs stabilization

Some URLs are not valid yet unless you add `beta/`, but they should be when 1.28 is released.